Printing press drive



Feb. 25, 1947. T. E. PlZzE PRINTING -rREss DRIVE Filed lay 5. 1943 4 Sheets-Sheet 1 l AnoRNEY Feb. 25, 1947.

T. E. FIAZZE PRINTINGTRESS DRIVE Filed lay 3, 1943 y T51-f 4 sheetsSheet 2 INVNTQR 7720/11455 Zazze- ATTORNEY Feb. 25, 1947. T, E. PMZZE' 2,416,495

1 PRINTING PRESS DRIVE lF1164 Hay s, 194:5 4 sheets-sheet s |NvEN-rn 75g/nas E azze ATTORNEY Feb. 25, 1947.- f. g. PlAzzE 2,416,495

PRINTING PRESS DRIVE v Filed May 3, 1943 4 Sheets- Sheet 4 ulllllun lll` www@ ATTORNEY Patented Feb. 2s, 1947 Thomas E. Plane, Lyndhurst, N. J., assignor, by

mes'ne assignments, to Champlain Company, Inc., New York, N. Y., a corporation of New York Application May 3, 1943, serial No. 485,462

(ci. i-152) 9 Claims. l This invention relates to adjustable speed mechanism for positively driving an output memberfrom an input member in any one of a multivplicity of selected speed lratios which diller minutely from one another and from the speed of the input' member, and to mechanism for ef fecting micrometric adjustments of phase of an driving trains from the common drive shaft to the feed roller couples means for adjusting the rotary speed output-input ratio of such trains.

l Such adjusting means commonly take one of two output member relative to an input member which, though individually very small, may be cumulatively of unlimited extent.

The invention is disclosed herein as incorporated in a web printing press of the rotogravure type, because it is useful in presses-0f this kind both in respect of the selection of speed and in respect of the adjustment of phase for securing and maintaining printing register, and because the invention has been especially contrived with reference to requirements of these presses. It is to be understood, however, that such disclosure is intended to be regarded as illustrative and not asv limiting in character.

In a rotogravure press a web is advanced through successive printing couples, each comprising a driven printing cylinder for printing in a single color upon each unit length of web, and an impression cylinder cooperative with the printing cylinder. The printing cylinders for a given job are al1 as nearly as possible of the same diameter, and yall are driven at the same rotary speed. All simultaneously used printing cylin ders run, therefore, at the same, or nearly the same, peripheral speed. Printing cylinders of different sizes are selected vfor different jobs in accordance ywith the form length required, the form length being equal to the circumference of a printing cylinder.

A feed roller couple unwinds the web from a supply reel and delivers it to the iirst printing couple, and a further feed roller couple deliversv I' the web from the nal printing couple to a takeup reel on which the web is rewound. 'I'he feedl rollers form permanentl elements of the machine, and means are commonly provided for adjusting `the rotary speeds of these rollers to cause the peripheral speeds of the rollers to be as nearly as possi-ble the same as the peripheral speed of whatever printing cylinders are currently in use.

To this end it is usual practice to provide a common drive shaft for the printing cylinders forms.

One oi' these consists of employing change gears which provideva positive and even drive. but which make available only driving ratios which diier substantially one from another. Each driving ratio necessarily differs from the nearest adjacent available ratio by the amount, at least, which is represented by withdrawing a gear from the train and substituting a gear having one tooth more or one tooth less than the withdrawn gear. If the Withdrawn gear, for ex' A The latter is jerky' and of variable strength in its application of the driving force.

In accordance with the present invention, it

is .proposed to provide a positive drive, but to make available a great number of speeds for the feed roller drive which differ from one another minutely. For example, instead of an interval between available drives corresponding to the addition or withdrawa1 of a whole gear tooth. the successively available drives may differ from one another by only a very small fraction of that amount. The drive ratio selected will depend ,upon the diameter of printing cylinder desired, and this in turn -may be adjusted to the desired value either by shaving or by electrodepositing a predetermined thickness of metal on the printing cylinder prior to embossing.

In theory the capability for, line adjustment thus provided enables a i positive drive to be secured which is in harmony with every printing 'cylinder diameter for which there can be any practical use. In actual practice, of course, perfection may notbe attainable', so that it is still desirable to make provision for adjusting the f upon the une A-2 of Fig. 1,1ooking1n the direcphase of each printing cylinder individually from time to time in relation to the web.

In actual practice, also, the web is passed through a drier after each printing couple, and this causes the web to contract in its progress through the press. The amount of contraction is not precisely predictable because of variable atmospheric conditions, and of other possible variations of operating conditions. Since contraction reduces the form length established by the rst printing cylinder, the form length reaching the second or any subsequent printing cylinder may be slightly less than the circumference of that cylinder. For this reason, also, it is desirable that means be providedv for adjusting the' phase of each printing cylinder relative to the web as the need for adjustmentappears, in order that practical printing register may be main tained.

It is a salient object of the present invention to provide simple, inexpensive and practical means for adjusting the rotary speed of a positively driven feed roller couple within narrow limits and by ne increments relative to the driving means therefor. e

It is a vfurther salient object of the present invention to`provide simple, compact, inexpensive and practical means interposed in the drive train y Since successive adjustments of the printing.

cylinder will generally be in the same direction, it is desirable that the adjusting means be capable of effecting a total adjustment of unlimited extent, and it is a feature of the present invention that the adjusting means provided has capacity for unlimited adjustment. This not only obviates the possibility of having to interrupt the operation of the press to set back the adjusting means to the starting point, but also obviates the necessity of setting back the adjusting means when the press is idle. Corrections can go on accumulating indefinitely in either direction.

Additional advantages of the drive unitv as disclosed are (1) that few gears are required for accomplishing the intended purpose; (2) that al1 gears are of substantial size and hence none is rei quired to run at excessive speed and none is subl jected to excessive wear; (3) that4 there is a minimum of backlash; (4) that the entire unit is of simple and extremely compact construction; (5) that epicyclic gearing is employed, providing a well balanced construction; and (6) that the regl a slightly aideront speed from the take-off feed rollers, to compensate for the shrinkage of the web in its progress through the machine.

Other objects and advantages will hereinafter appear. Y In the drawing forming part of this specification:

Fig. 1 is a fragmentary, longitudinal, vertical, sectional view through a printing register adjusttion of the arrows: Fig. 3 is a fragmentary, vertical, longitudinal,

sectional view through a speed converting unit embodying features of the invention;

Fig. 4 is a vertical, sectional view taken upon the line Q of Fig. 3, looking in the direction of the arrows;

Fig, 5 is a vertical, sectional view taken upon the line 5-5 of Fig. 3,'looking in the direction of the arrows; and

Fig. 6 is a diagrammatic view of a rotogravure which the printing cylinder of a printing couple is driven. The differential unit comprises an input gear, two planet gears 5 and 6, and an output gear 1. The planet gears '5 and y6 are carried upon a shaft 8 which is eccentrically mounted with relation to the gears 4 and 7, the shaft being carried by -a worm gear 9, which is in mesh with a worm I0 and is normally locked against rotation by the worm I0. The drive ratio from the gear 4 to the gear 5 is not the same as that from the gear 6 to the vgear l, and consequently it is characteristic of the disclosed differential that the output shaft 3 is driven at a different rotary speed from the input shaft I when the worm gear 9 isy held stationary by the worm i0, This change of rspeed introduced `by the differential 2 is not wanted, and accordingly provision is made to compensate it 'by interposing gearing whose outputinput ratio is effectively the reciprocal of that of the differential u nit, either between the main drive shaft of the machine and the shaft I, or between the shaft 3 and the drive shaft of the print-I ing` cylinder.

'I'he change of speed effected by the differential unit 2 is introduced, even though it must be cancelled elsewhere, for the reason that it is a contributing factor in providing a very superior phase adjusting unit, as will be brought out morev clearly after the illustrative construction has been described in detail.

The illustrative unit comprises a principal housing member II, not much larger than gears 4 and 1, which includes a supporting base or web I2. .A secondary housing member I3 is secured to the housing member II by screwsv I4. An end housing member I5 is secured to the housing member II by screws I6, and an end housing member II is secured to the housing member I3 by screws I8. The shaft 4 extends into the housing and has the gear 4 formed integrally upon l the inner end of it. A nut I 9 is threaded onto the shaft I, and is held in xed position by a lock washer 20, so that it may serve as a thrust member for holding in place certain parts which are about to be described. Lock washer 20 includes a ing unit which embodies features of the invention,

thevsection being taken on the line I-I of Fig. 2

.looking in the direction of the arrows;

24 and 25 of ball bearings 26 and 21. A spacer Y sleeve 28 is interposed between the bearing members 24 and 25, and the assembly of inner bearing members 24, 25 and spacer sleeve 28 is held securely assembledA without freedom for end play between a shoulder 29 of the shaft I, which bears against the inner end portion of bearing member 25, and the nut I9, which bears through the lhousing member I through the washer 29.

Worm gear 9 is rotatively mounted in a bearing portion 33 of the housing member II, being held against endwise movement by engagement with a shoulder 34 of the housing member II and with an end face 35 of housing member I3.

Gear 9 supports the shaft 3 in ball bearings 33 and 31. The outer bearing members39 and 4I) are mounted at opposite sides of an internal annular ange or boss 4I of the gear 9`, and the inner bearing members 42 and 43 are mounted at opposite sides of a spacer sleeve 44. The inner bearing members 42 and 43 are locked against endwise movement -by engagement with hub portions of the gears 5 and 3.

Shaft 3 is formed at the left-hand end thereof with ahead portion 45 which is seated in a recess 43 of the gear 5. The gear 5 is secured to the shaft 3 by means of a key 41. The shaft 3 extends through the gear 5, the ball 'bearings 33 and 31, and the gears 3. A nut 48, threaded on a reduced end portion 49 of the shaft 3 and held in place by a lock washer 50, `retains the shaft 3 and the associated gears 5 and 3 in assembled relation. I

The mounting of gear 1 and shaft 3 in housing member I3 is the same as the mounting of gear 4 and shaft I in housing member II. The shaft 3 is supported in the inner bearing members 5I and 52l of ball bearings 53 and 54, the bearing' members 5I and 52 being spaced frommne another by an interposed spacersleeve 55.

Outer bearing members 53 and 51, like ball bearings 53 and 54, are mounted at opposite sides of an internal annular sleeve or boss 53 of the housing member I3. A nut' 59, threaded onto shaft 3 and held in place by lock washer 39. which is similar to lock washer 29, bears through the washer against the outer end of the inner bearing member 52, while the inner end of bearing member 5I bears against a shoulder 3I of shaft 3. End housing member I1 bears against the outer end of outer bearing member 51'.

Worm I3 is fast upon a worm shaft 32, and is located in an upper extension 33 of housing member II. At one side .of the worm I0, shaft 32 is revolubly supported in a bearing bore 34 of housing extension 33. End thrust of the shaft 32 is transmitter through a ball 35 to a wear opposite side of the worm I0, the shaft 32 .extends through a bearing bushing l31 whichis secured to housing extension 33 by means of screws 33.

As has been noted, the gear 9 is normally locked against rotation by the worm III. It may,

however, be rotated by the worm to'carry thek bgear 3, operation Aof the planet gears through the worm I0 would be ineffective to produce any change of phase between the gears 4 and 1. but

' would instead simply cause the gear 1 to be rotated in unison with the gear 4 or to stand sta.-

tionary if gear 4 were held stationary during such adjustment.

The fact that the output-input ratio of'gears 1 and 4 is nearly not quite unity when gear 9 Is locked is an important point from the standpoint of attaining the objects of the invention. This makes possible a very fine and precise adjustment of phase and thus brings about arvery fine,

and precise adjustment of printing register.

In the illustrative construction, for example, the gear 4 may be formed with fifty teeth, the gears 5 and 3 with 43 teeth each, and the gear 1 with 51 teeth. The gears 5 and 3 may be of identical diameter, and the gears 4 and 1 may be of identical diameter. To this end either or both of the gears-5 and 3 is desirably made as a mongrel gear capable of havingintermeshing and driving engagement with either'a fifty tooth or a fty-one tooth gear.

On'the basis of the illustrative figures as to numbers of teeth, the output-input rotary speed Y ratio of gears V1 and 4 will be 50/51, and as heretofore pointed out this change of speed is elsewhere compensated or counterbalanced by the inclusion in the same train of a gear combination Y tinuously cancelled by the compensating step-up plate ss located 1n the bearing bore el. At the the bearings of gears 5 and 3 at excessive speeds. Y

drive.

The effect of operation of the Worm I9 can best be analyzed by assuming that such operation occurs when the gear 4 is held stationary, although the effect of such operation in so far as it affects phase adjustment will be precisely the same whether the gear 4 be stationary or moving.

Whenever the worm wheel 9 is rotated by operation of the Worm I0, one complete rotation of of gears 4 and 1. This, in turn, will cause the point of deepest tooth penetration of gear 5 with gear 4 and of gear 3 with gear 1 to progress throughexactly one complete revolution. The gear 5 will have engaged fifty teeth of the gear 4 and the gear 3 willlikewise have engaged fifty teeth of the gear 1 This is one less tooth than the'completev number of teeth on the gear 1, however, and hence the result'of the operation will have been to turn the gear 1 one tooth space relative to gear 4 in the same direction in which gear 9 is turned.

The output-input ratio of gear 1 to gear 9 is, therefore, ,1/51. This large step-down ratio is effected through the medium of' only four gears, all of nearly the same size. When the. fact is taken into account that there may be an equally large or even a considerably largerV step-down from worm shaft 32 to worm wheel 9, it will be appreciated that phase adjustment of extreme ilneness and extreme precision is made available, although no parts of precision manufacture are involved in the construction.

It is not essential to the practicing of the invention that mongrel gears be employed, nor that-the rule of equal diameters be observed between the gears 5 and 3 and the gears 4 and 1.

Straight spur gearing, internal for the gears 4 and 1, and external for the gears 5 and 0, may be utilized if the diameters of the several gears are properly related to one another. The` formula for'the relationship of the gearsln such a case may be briefly indicated as follows:

If R4, Re, Re and R1 be taken as the radii of the respective gears 4, 5, 8 and l, and T4, Ts, Ts

and Tv be taken as the number of teeth of the respective gears 4, 5, 6 and 1, then R4 T4 and mulas whether or not the numbers of teeth arbitrarily selected are actually available for a dif- 1 ferential unit of compact construction and sound design. The output-input ratio of gear l to gear 4 is t R5,R7 T5.T7 and when Te=T5 this becomes y vT1 3 The output-input ratio of gear 1 t0 gear 9 is and when T=T5, thisbecomes T7 I It is possible by making the numbers of teeth 4of the gears 5 and 6 different fromA one another 1 to bring about a compound step-down from gear or, if desired. it may be equipped withy a small operating motor.

A motor may be advantageously employed for adjusting the register of the several printing cylinders by remote control from a common station at which the operator is in a position to View the resulting work of the entire press and judge which colors are out of register and to what 'ex-1a tent adjustment is required. By using reversible motors and' providing .switches in the operating' circuits of the several motors at the common control station, the operator is enabled very quickly to adjust any selected printing cylinder forward or backward relative to the web to any extent that he considers desirable.

The motor method of operation is also ady vantageous for securing automatic adjustment of register in responsevto photoelectric mechanism in accordance with a principle well understood in the art. .f

The speed converting unit of Fig. 3 is in many respects similar to the printing register adjusting device of Figs. 1 and 2. It comprises an input .shaft la for tra/nsmittingmotion througha differential unit 2a to an output shaft 3a. The difierential'comprlses an internal gear 4a for driving planet gear 5a and a planet gear 6a fast with 9 to gear 1. It is not generally desirable, however, to resort to such'a scheme for securing an enhanced step-down ratio. Asimple output-input ratio of gears 'l and 4 such as 50/5I can be compensated by a simple gear couple and without increasing the number of gears which would otherwise be present, but a compound reduction is not practically requiredas a rule, and it canI be compensated only by a compound gear train with its attendant drawbacks. It is generally to l be preferred, therefore, that the number of teeth of gear 5 be made equal to the number of teeth of gear 6, and that gear I have one tooth more g or one tooth less than gear 4, since this ordinarily l provides a` sufficiently ne adjustment for all practical purposes..

Because of the large size of gears '5 and 6 relative to gears 4 and 1, and because of the small number of gears employed, there is a minimum of backlash in the differential unit. Be-

cause of this sam'e point, there is no excessive wear upon the gear teeth and gear bearings, and no ,l excessive strain upon any of the parts.

The worm |0 is desirably a single thread worm l of sufficiently low pitch to serve as a positive locking means for the worm gear 9. This is advantageous because it assures that any register once established will not ybe accidentally disturbed through slipping or creeping of the parts.

The worm shaft 62 may be manually operated,v

v planet gear 45a, for driving internal gear la.

lIn this instance gear 9a is not used for effecting -phase adjustment of shaft 3a relative to shaft la, but is used for modifying the output-input rotary speed ratio of shaft 3a relative to shaft la.

The gear 9a is constantly driven from the shaft la. in any one of a multiplicity of selected gear ratios, and the input from gear 9a is combined l with the input from gear 4a by the differential unit to produce the desired resulting output speed,

all as will be more fully explained after the construction of the unit has been described in detail.

The gear unit'l comprises a housing |0| which includes a central housing member |02, and side housing members |03 and |04 which are secured to the housing member |02 by screws |05. Shaft a extends through housing member |03 .and is revolubly mounted in a bearing sleeve |06. Shaft 3a extends .through housing member |04 `and is revolubly mounted in abearing sleeve I0?. Shafts la and '3a have integrally formed upon their inner ends the internal gears 4a and la. The central portions of the inner ends of the shafts la and 3a are formed with recesses in which roller bearings |08 and |09 are mounted. The end portions of shaft 8a are revolublyvsupported in the roller bearings` Shaft 8a includes an enlarged eccentric portion ||0 which is revoluble in a bearing sleeve of gear 5a. Gear 5a includes a sleeve portion ||'2 which is revolubly mounted in a bearing sleeve ||3 of gear 9a. Gear 9a is :revolubly mounted` in bearing ring segments I |4 vwhich are secured toA opposite sides of an internal flange ||5 of heusing member |02. Bearing segments I|4 carry lining ring segments I6 of suitable bearing metal. The gear 6a is aixed to a reduced end portion of sleeve ||2 by means of a feather Ill.

A gear H8 fast upon shaft la transmits motion through intermediate gears H9 and |20 to a gear `|2| which is fast upon a shaft |22. Shaft |22 has fast upon it a gear |23 through which gear 9a is constantly driven.

The intermediate gear I I9 is revolubly mounted upon a stub shaft |24 carried by housing member |03. Intermediate gear |20 is carried by a bent lever |25 which is mounted with capacity for rocking movement upon stub shaft |24. The tail portion of lever |20 is formed with an arcuate couple 200 which comprises a driven printing cylslot |21.' A headed bolt |23 is passed through .the slot '|21 and threaded into housing member |03 for clamping the lever in different selecte I positions of adjustment.

Gear |2| is mounted on shaftl |122 with capacity for quick and easy removal and replacement so that gears of different sizes may be substituted. Gear |2| is mounted on a square end of shaft |22 and is held in place by a washer |24 and a bolt |30, the bolt being screwed into the end of shaft |22.

' As the partsare illustrated, gears ||8 and |2| are of equal size, and hence shaft |22 will be driven in the opposite direction but at the same rotary speed as shaft la. In the illustrative construction gear |23 is of the same size as gear 8a, and hence gear a will be driven in the same dilis rection and at the same rotary speed as shaft |a.

Gears 4a, 5a, 6a and 1a may for illustrative purposes. be taken as having v50, 43, 43 and 51 teeth respectively, as in the illustrative example previously given with reference to gears 4, \5, 0 and 1. It will be remembered that, if gear 4a were driven and gear 9a held stationary, the output input ratio of gear 1a relative to gear 4a would be 50/51, and that if gear 4a were held stationary and gear 9a driven, the output-input ratio of gear 1a relative to gear 9a would be 1/51. When the gears 4a and 9a are driven in unison, the gear 1a is caused to rotate in unison with the gear 4a, and hence the output-input ratio of shaft 3a relative to shaft la is unity.

If, however, the gear |2|,Iwhich may be assumed to have 50 teeth, were replaced by a gear.

having 51 teeth, the output-input ratio of shaft |22 relative to shaft la would become 50/51. In

other words, shaft |22 would make 5%1 revolution during one revolution of shaft la, and since one revolution of shaft |22 accounts for exactly one tooth space advance of gear 1a, 5%1 of a revolui given.

tion of a shaft |22 would account for 50/51 of one of the 51 equal tooth spaces of g'ear 1a. The output-input ratio of gear 3a to gear la would then fall short of unity by l/l of a tooth space of gear 1a or iff-,1 of $61 of a revolution for each revolution of shaft a. The substitution of a 52 toothgear for gear |2| would nearly double this measure of inder 201 and a cooperating impression cylinderweb to a take-up reel 220 on which it is rewound.

Although more than two printing couples would ordinarily be present, the Anumber illustrated serves adequately for disclosing the invention.

Feed roll couples 203 and 2|9, and printing cylinders 201 and 2|4 are all driven from a common.

drive shaft 22|. Printing cylinder 201 is driven from shaft 22| through a pair of bevel gears 222 and 223 which are fast, respectively, on shafts 22| and. Shaft drives shaft 3 through unit 224 of Figs. 1 and 2, and shaft 3, in turn, drives printing cylinder 201. The drive of printing cylinder 2|4 is identical with that of printing cylinder 201. Corresponding reference characters have accordingly been applied to corresponding parts, and no further detailed description will be Thedrive of feed roll couple 203 from shaft 22| is transmitted through a change gear unit 225 to shaft la, and thence through speed conversion unit 220 of Figs. 3 to 5,Y and shaft 3a, tothe lower. roller of couple 203. The unit 225 comprises a bevel gear 221 keyed on shaft 22|, a bevel gear 228 in mesh therewith, and a shaft 229 on which the bevel gear 228 is xedly mounted, and a gear- 230 fast on the shaft 229. Gear 230 drives a gear 23| fast on shaft la. The unit`225 may be adjusted longitudinally of the shaft 22| and fixed in any selected position of adjustment. The gear 230 may be readily replaced on shaft 229 by gears having different numbers of teeth.

Drive roller couple 2|9 is driven from shaft 22| ence characters have accordingly been applied to difference of rotary speeds, and the continued i substitution of gears for. |2| each having one tooth more than its predecessor of the series would produce successive changes corresponding toa small fraction of a tooth space per revolution. The total range of adjustment made available by substitution of gears for gear I2 I may conveniently exceed one-half of a tooth space of gear 1a. The fact that the range of adjustment is thus limited does not mean that there are gaps left in the series of available fine speed adjustments,

,as will be pointed out subsequently in connection with Fig. l3.

It will be evident that the described speed conversion unit makes it possible to reduce the interval between successively available speeds to a very minute amount,vand that it provides a manifold increase ofavailable speeds.

In Fig. 6 a rotogravure press is diagrammatically illustrated in which each printing cylinder is driven through a phase adjusting unit which may be the unit of Figs. l and 2, and each feed roller couple is driven through a speed converting unit which may be the unit of Figs. 4 to 6.

The paperweb 20| i's drawn from a supply'reel 202 by a feed roller couple 203, and passes thence over guide rollers 204 and 205 to a ilrst printing corresponding parts. and no further detailed description will be given The use of units 224, 225 and 226 in the press can be best explained by assuming an initial set-up in which the diameters of printing cylinders 201 and 2I4 ,are twice the diameter of the feed rollers of the couples 203 and 2|9, and an adjustment of unitv 226 to cause the feed rollers to' turn at twice the rotary speed of the printing cylinders. Permanent bevel gears 221 and. 228 may be of equal size, and a gear 230 may be chosen having a diameter twice as great as the diameter of gear 23|. Unit 226 is then set to cause shaft 3a to run in unison with shaft la, and this causes the feed rollers of unit 203 to travel at twice the rotaryspeed of shaft 22|.

It is desirable then that the printing cylinder 201 turn at the same rotary speed as shaft22i, so that the printing cylinder will normally run at the same peripheral speed as the rollers of couple ^203. The permanent gears 222 and 223 are not of shaft 3 to shaft to be 50/51. Shaft 3 and printing cylinder 201 will, therefore, run at the the driving rollers must be correspondingly in creased. If the change corresponds to a change of exactly a whole number of teeth of 'gear 230 of unit 225, an appropriate substitute for gear 231i` is chosen and unit 226 needl not be disturbed. If the change of speed involves a fraction of a tooth space of gear 230 or a whole number of tooth spaces plus a fraction, it will also be necessary to effect a gear substitution in unit 226 in order to produce the desired speed of the rollers of couple 203. The gear 230 may always have at least twice as many teeth as the gear la, and since the sucl lcessi've gears 230 may be made dierent from one another by a single tooth, the fact that the total range of adjustment of unit 22S as illustrated corresponds only to approximately onehalfa tooth of gear'la does not cause objectionable gaps to be left in the series of available speeds.

I have described what I believe to be the best embodiments of my Iinvention. I do not wish, however, to be lconfined to the embodiments shown, but what I desire to cover by Letters Pat-h ent is set forth in the appended claims.

I claim:

1. A differential gear unit comprising a pairl of revolubly mounted coaxial internal gears and a pair of coaxial planet gears connected in xed relation to one another, each in mesh with one of the internal gears, the output-input ratios of the intermeshing gear pairs being nearly but not.

quite reciprocals of one another, the planet gears diameters of the internal gears that they inter-- sect the common axis of the internal gears, and

l means supporting the planet gears eccentrically l within the internal gears, said means comprising 1 an external gear disposed between, and concen tric with, the internal gears.

. 2. A diierential g'ear unit comprisinga pair` i of coaxial internal gears and a pair of coaxial i planet gears connected in xed relation to one another, each in mesh with one of the internal 3 such large diameters in relation to the diameters of the internal gears that they intersect the common axis of the internal gears. and a rotary member supporting the planet gears eccentrically within the internal gears and a casing providing bearing means in which the periphery of the rotary planet-gear-supporting member is revolubly mounted.

4. A differential gear as set forth in el 1f in which each of the internal' gears has many teeth but one of them has one more tooth than the other, and in which the planet gears have equal numbers of teeth.

5. A dierential gear as set forth in claim i in which the internal gears are of equal diameters .and each of them has many teeth but one oi' ternal gears, a pair oi coaxial planet gears connected in -lxed 'relation to one another, and in being of such large diameters in relation to the` 1 gears, the output-input ratlos of the intermeshe 1 ing gear pairs being nearly but not quite reciprocals of one another, the planet gears being of mon axis of the internal gears, a worm gear rotatably supporting the planet gears eccentrically within the intemal gears, and a worm inv mesh with the worm gear and fnormally locking another, each in mesh with one of the internal '1 gears, the output-input ratios oi. the intermeshing g gear pairs being nearly but not quite reciprocals of one another, the planetrgears being of `such i large diameters in relation to the diameters of the internal gears that they intersect 3.1 60mmesh respectively with the input and output internal gears, the.. meshing gear Apairs being nearly but not quite reciprocal pairs, so that the normal output-input ratio differs slightly from a one to one ratio, means in said train for cancelling the difference between said ratio and a one to one ratio, a rotary member coaxial with the internal gears for supporting the planet gears for rotaagainst planetary movement, but operable at any time -to turn the rotary member forward or backward.

7. A transmission unit comprising, in combination, a drive shaft, a differential unitfdriven thereby, comprising coaxial input and output interna] gears, a pair of coaxial planet gears connected in xed relation to one another, and in f mesh respectively with the input and output internal gears, the output-input ratios of' the meshing gear pairs being nearly but not quit reciprocals of one another, a carrier gear for the planet gears coaxial with the internal gears andA suD- porting planet gears with their common axis offset slightly from the axis of the internal gears,y and a sidetrain from. the drive shaft to the carrier gear yincluding a, change gear unit whereby the carrier gear, whose maximum contribution to the output rate is but a minute fraction of the total' output rate, may be itself varied by minute fractional amounts.

8. In a gravure press having a drive shaft, and printing cylinders; a novel drive train from the drive shaft to a printing cylinderwhich includes a running register adjusting means, said running register adjusting means including a differential gear which comprisesl normal input and output arms and a normally locked adjusting arm which is operable at will, the normal output-input ratio of said diierential gear differing from a. one to one ratio by a minute fractional amount, and

means in said train for compensating the difference between the normal output-input ratio and a one to one ratio. y

9. Ina. press having a drive shaft, feed rolls, a printing cylinder, and means for establishing a positive normal drive' from the drive shaft to the printing cylinder; vthe novel mechanism for establishing a predetermined positive drive from the drive shaft to a feed roll in accordance with effect equal only to a. single tooth space movement of .one of the internal gears, and a geartrain operated from the drive shaft for, driving the carrier gear, said train comprising a change gear unit whereby the rate of operation of the carrier gear can be varied to change the output by amounts corresponding to minute fractions ofa single tooth space per revolution of the output internal gear. A

THOMAS E. PIAZZE.

REFERENCES crrED Thel following references areof record in the file of this patent:

Number Number UNITED STATES PATENTS Namev Date Miller et al. July 31, 1923 Ahlm et al. June 4, 1929 Sterling Sept. 10,1929 Juhasz Dec. 18, 1928 Wolf Mar. 6, 1928 Weiss v Sept. 22, 1936 Cossar Dec. 1, 1903 Veeder Apr. 29, 1930 Veeder Oct. 22, 1895 Coy 1 Nov. 9, -1943 Robin et a1. Mar. 27, 1945 Leeuw y Sept. 5, 1905 Cafrey 1 Apr. 15, 1902 FOREIGN PATENTS Country Date German Oct. 2', 1924 

